A known air drier for an air suspension is disclosed, for example, in JP2002-119824A (hereinafter referred to as Reference 1). The air drier dries air compressed by an external compressor and sends the compressed dry air to an external air control system. The air drier includes a housing having an approximate tubular shape, and a desiccant agent filled within the housing. A compressor-side port connecting to the external compressor is formed in an intermediate portion of one of axial end surfaces of the housing and a control-system-side port connecting to the air control system is formed in the other of the axial end surfaces. The desiccant agent filled within the housing dehumidifies the air passing from the external compressor through the housing to the air control system. When the desiccant agent dehumidifies the compressed air, moisture removed from the compressed air is absorbed into the desiccant agent. As the volume of the absorbed moisture in the desiccant agent increases, the dehumidification function of the desiccant agent gradually deteriorates. For example, in a case where the air drier is continuously in use, the air from which the moisture is removed by the desiccant agent is filled in the external air control system and is thereafter returned to the external compressor via the air drier according to need; thereby, the absorbed moisture in the desiccant agent dries. Accordingly, the volume of the absorbed moisture in the desiccant agent decreases to thereby dry the moist desiccant. Consequently, the dehumidification function of the desiccant agent may be regenerated. In addition, according to Reference 1, even when being arranged in a vehicle or the like in a condition where the axial end surfaces of the housing face a lateral direction of the vehicle or the like, the air drier may surely remove dry dew condensation water in the housing therefrom.
Further, a known water remover disclosed in JP1995-328373A (hereinafter referred to as Reference 2) includes a liquid separator in which a tangential inflow cyclone separator and a water-collection housing are arranged, and a drier with which silica particles are filled. Gas including vapor-phase moisture and liquid-phase moisture flows through the tangential-inflow cyclone separator. The tangential-inflow cyclone separator includes an internal cylindrical portion having a flow passage. The flow passage of the internal cylindrical portion expands toward an opening of the tangential-inflow cyclone separator. A chamber having an expanded flow passage is formed in the water-collection housing (the chamber will be hereinafter referred to as the expanded-flow-passage chamber). The internal cylindrical portion of the tangential-inflow cyclone separator protrudes into the expanded-flow-passage chamber; thereby, an annular groove is formed in the liquid separator. The liquid-phase moisture around the internal cylindrical portion protruding into the expanded-flow-passage chamber is collected in the annular groove of the liquid separator.
Furthermore, a known dehumidifier for a braking system serving as a combined air and hydraulic pressure braking system for a vehicle is disclosed in JP1993-201329A (hereinafter referred to as Reference 3). According to the braking system described in Reference 3, air compressed by an air compressor is stored in an air tank and a braking operation is performed by the air compressed in accordance with a degree by which a driver presses a brake pedal. The dehumidifier includes an air drier and an electrostatic clarifier. The electrostatic clarifier removes oil mist included in the compressed air therefrom. Then, the air drier removes moisture included in the compressed air therefrom by means of a desiccant agent. Thus, according to the braking system according to Reference 3, the oil mist and the moisture that are included in the compressed air are removed therefrom; thereafter, the compressed air is stored in the air tank.
The air drier disclosed in Reference 1 has a large size as a whole; therefore, a large space is required when arranging the air drier in the vehicle. In addition, the water remover disclosed in Reference 2 includes the tangential-inflow cyclone separator and the dehumidifier disclosed in Reference 3 includes the electrostatic clarifier; therefore, the water remover and the dehumidifier have complex configurations, resulting in cost increases.
A need thus exists for an air drier for an air suspension of a vehicle, which is not susceptible to the drawback mentioned above.